Saw components tailoring had initially affixed to shirt (5)
I believe the answer is:
teeth
'saw components' is the definition.
(saw blades have teeth)
'tailoring had initially affixed to shirt' is the wordplay.
'initially' indicates taking the first letters.
'affixed to' means one lot of letters go next to another.
'shirt' becomes 'tee shirt' (tee shirt is a kind of shirt).
The first letters of 'tailoring had' is 'th'.
'th' after 'tee' is 'TEETH'.
(Other definitions for teeth that I've seen before include "Effective power" , "Genuine effectiveness" , "symbols of legal power?" , "Dentition" , "Saw or gearwheel items" .)